Door systems for low contamination, high throughput handling of workpieces for vacuum processing

ABSTRACT

A workpiece handling system with dual load locks, a transport chamber and a process chamber. Workpieces may be retrieved from one load lock for processing at vacuum pressure, while workpieces are unloaded from the other load lock at the pressure of the surrounding environment. The transport chamber has a transport robot with two arms. Processed workpieces and new workpieces may be exchanged by a simple under/over motion of the two robot arms. The transport robot rotates about a central shaft to align with the load locks or the process chamber. The robot may also be raised or lowered to align the arms with the desired location to which workpieces are deposited or from which workpieces are retrieved. The two load locks may be positioned one above the other such that a simple vertical motion of the robot can be used to select between the two load locks. The two load locks and transport robot allow almost continuous processing. Additional process chambers may be added to the transport chamber to further increase throughput. Each stage of the workpiece handling system may also be designed to handle multiple workpieces, such as two side by side workpieces. Throughput is increased while allowing shared machinery to be used. Linear and rotational doors may be used for the load locks to provide a simple, compact design.

REFERENCE TO RELATED APPLICATION

The present application is a divisional of U.S. application Ser. No.09/200,660 filed Nov. 25, 1998, which issued as U.S. Pat. No. 6,315,512,which claims priority from U.S. provisional application No. 60/067,299filed Nov. 28, 1997. Provisional application No. 60/067,299 is herebyincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The field of the present invention relates in general to vacuumprocessing of workpieces. More particularly, the field of the inventionrelates to systems and methods for low contamination, high throughputhandling of workpieces including processing at a pressure different fromatmospheric. Examples of such workpieces might include semiconductorwafers or flat panels for displays for which vacuum processing isusually required.

BACKGROUND OF THE INVENTION

The increased cost for semiconductor manufacturing equipment and factoryfloor space has driven equipment vendors increasingly to compete on theproductivity of their products and thus to have to increase the numberof workpieces, such as wafers, that can be processed in any piece ofsuch equipment per hour (throughput). There are three central factorsthat determine workpiece throughput: the time spent actually processingthe workpieces (e.g. removing photoresist, implanting ions, etc.), thenumber of workpieces that can be simultaneously processed, and theamount of time that elapses between removing processed workpieces from aprocessing chamber and inserting unprocessed workpieces into thechamber.

In some conventional workpiece processing systems, there may be asignificant delay between the time when processed workpieces are removedfrom a process chamber and the time when the new unprocessed workpiecesare provided to the process chamber. For instance, some systems use asingle robot arm to remove and insert workpieces. The robot arm mustfirst align with the processed workpiece, remove the processed workpiecefrom the processing chamber, move to align with a storage area forprocessed workpieces (which may involve a 180 degree rotation), depositthe processed workpiece, move to align with a storage area containingunprocessed workpieces, retrieve an unprocessed workpiece, move to alignwith the processing chamber (which may involve a 180 degree rotation)and deposit the unprocessed workpiece in the processing chamber. Thecumulative time required for all such steps may be large resulting in asubstantial delay between the time when a processed workpiece is removedfrom the processing chamber and the time when a new unprocessedworkpiece is provided to the processing chamber. In addition, each timethat a batch containing a given number of workpieces is processed, theseworkpieces must be removed through a load lock to transit the pressuredifferential between atmosphere and process pressure and a new batchmust be loaded into the processing environment. The time required forremoving and loading batches and for pressurizing or evacuating the loadlock also decreases throughput.

One system that has been designed to overcome some of the disadvantagesof conventional systems is the currently available Aspen™ systemavailable from Mattson Technology, Inc. which is used to processsemiconductor workpieces. In the current Aspen™ system, a workpiecehandling robot has two pairs of workpiece support paddles facing inopposite directions as shown in FIG. 1. Two new workpieces are loaded onthe paddles on one side of the robot. Then two processed workpieces areremoved from the process chamber on the paddles on the opposite side ofthe robot. The robot rotates once and then deposits the new workpiecesin the process chamber and puts the processed workpieces back in thecassette which may hold from 13 to as many as 26 workpieces. Once acassette of workpieces is processed, the cassette is removed and a newcassette is provided through the load lock mechanism shown in FIG. 2. Asshown in FIG. 2, a rotation mechanism is used to exchange cassettesquickly in an outer load lock indicated at 202.

Another system designed to overcome some of the disadvantages ofconventional systems is shown in FIGS. 3A and 3B and is described inU.S. Pat. No. 5,486,080. In this system two separate robots 62 and 64move independently of one another to transport workpieces between animplantation station 25 and load locks 22 a and 22 b. An intermediatetransfer station 50 is used to transfer the workpieces. FIG. 3B is aworkpiece path diagram showing the transport steps used to moveworkpieces in the system. While a first robot transports an unprocessedworkpiece from the transfer station 50 to the implantation station 25, asecond robot transports a processed workpiece from the implantationstation 25 to one of the load locks 22 a or 22 b. While one load lock isbeing used for processing, the other load lock can be pressurized,reloaded and evacuated.

While the above systems improve throughput and decrease down time forpressurizing and evacuating load locks, reductions in system size,complexity, and cost while maintaining or improving throughput are stillneeded. For instance, the system of FIGS. 3A and 3B uses two separaterobots and a transfer station all of which take up space. However, it isdesirable to decrease the size of workpiece processing systems to theextent possible, because the clean room area used for the system is veryexpensive to maintain. In addition, separate drive mechanisms which maybe used for the two robots would be expected to be more complicated andexpensive than a system that employs only one drive mechanism.

In addition to throughput, size, complexity and cost, a fundamentalconstraint on workpiece handling systems is the necessity to avoidcontaminating workpieces. Very small amounts of contaminants, such asdirt or dust can render a workpiece unusable and the size and numbertolerance for particulate contaminants continues to decrease asworkpiece geometries decrease. Workpiece processing equipment mayintroduce contaminants in a variety of ways. For example, particles maybe shed when two pieces of machinery rub or touch. It is important tominimize the exposure of the workpieces to such contaminants duringhandling and processing.

It is a particular challenge to design doors that minimize particlesgenerated by friction. Doors open and close to allow workpieces to passbetween the ambient (usually a clean room environment) to a sealed (andpossibly evacuated) chamber or between two chambers. Opening and closingthe doors may involve mechanical mechanisms that create particles or maygenerate particles when two surfaces are pushed together to close thedoor. It is desirable to decrease the number of particles generated bysuch doors to reduce the likelihood of contaminating workpieces. Inaddition to avoiding contamination, it is desirable in many instances touse a door that does not occupy much space, thereby reducing the overallsize of the system and conserving valuable clean room space.

In summary, there is a need for a workpiece handling system with highthroughput but that does not entail relatively complicated or expensivemechanisms, or mechanisms that occupy a relatively large amount ofspace. There is a further need for a workpiece processing system withreduced particle generation and workpiece contamination. Withoutlimiting the foregoing, there is a need for door assemblies for use insuch systems which reduce the potential for contamination and occupy arelatively small space. Preferably a workpiece handling and processingsystem would satisfy all of the foregoing needs.

SUMMARY OF THE INVENTION

Aspects of the present invention provide a workpiece processing systemincluding multiple load locks, a workpiece transfer chamber and one ormore process chamber(s). In these aspects of the invention, the core ofthe system consists of the aforementioned multiple load lock stations,which may be stacked vertically and act as buffers between a workpiecehandler at atmospheric pressure and another workpiece handler at anotherpressure typically closer to the pressure at which the processes aredone. In another embodiment each load lock may function independentlyfrom the other(s). Hence, one may be open to atmosphere where a handlerunloads or reloads workpieces while other(s) operate, for example, inpartial vacuum, allowing a vacuum handler to supply workpieces to andfrom the process chamber(s). Additionally, the load locks may providethe capability to cool post process workpieces prior to or during theirpressure transition from the reduced pressure of the load lock toatmospheric pressure. This functional independence makes such a systemcapable of providing a steady supply of pre-processed workpieces for thevacuum handler thus achieving high throughput in nearly continuousworkpiece processing.

In another embodiment, a controlled mini-environment can be created onthe atmospheric side of the load locks to provide a clean, particle freevolume for loading or unloading workpieces. Air filtration systemsand/or laminar flow hoods can be incorporated for the purpose ofcontamination control. Multiple workpiece-holder docking stations can bemounted to the enclosure, creating a supply of pre-processed workpiecesto the system.

In another embodiment, a robotics handler can operate in themini-environment and bring workpieces from their holders (which may becalled cassettes) to the load locks and back again. This handler canutilize any combination of compound or individual rotational, vertical,and horizontal movements to selectively align with the workpiececassettes or load locks for the purpose of transferring workpieces. Therobot handler can have two sets of paddles, or other devices intendedfor retaining the workpieces during said transport. One set may consistof multiple, vertically stacked paddles, while the other may be a singlepaddle situated below the others. Each set is capable of independent ordependent linear motion such that any combination of the two can be usedto transport workpieces to and from the load locks. Additionalcomponents can be mounted to the robot, or be made accessible in themini-environment. These stations could provide operations such asworkpiece identification or any other pre- or post-process inspection.

In another embodiment, a linear door mechanism may be used to seal onedoorway of each load lock. An extractable door plate contained in ahousing may be extended against the doorway for sealing or retracted forunsealing. The door plate and housing may then be raised or lowered toprovide access for workpieces to pass through the doorway. If load locksare positioned above one another, the door of the upper load lock mightraise when opened and, conversely, the lower door might drop to providea pathway for workpiece transfer.

In another embodiment, dual or multiple load locks can be stackedvertically to minimize the system footprint. Each load lock may containshelves adjacent to which workpieces can be placed and staged. Theseshelves may be situated such that workpieces are contained next to andon top of one another. Workpiece temperature could be controlled throughthermal contact with the shelves which may be heated or cooled bygaseous conduction and radiation. Gases might also be directed over theworkpieces, prior to or after processing, to achieve desiredtemperatures.

In another embodiment, a rotational door may be used to seal the otherdoorway of each load lock. This door may be extended against the doorwayfor sealing or retracted for unsealing. Once decoupled from the doorway,the door may rotate up or down to allow workpieces to pass through. Thedoor of the upper load lock may rotate upward when opened and the lowerload lock door may rotate downward. The compactness of the door'soperation allows for vertically stacked load locks occupying minimalspace.

In one embodiment a robot handler residing in a central transferchamber, with pressure closer to process chamber pressure thanatmospheric pressure may be utilized to transport workpieces from theload locks to the process chamber(s) and back to the load locks afterprocessing. Such duties may be shared by two robotic arms utilizingcommon compound or individual vertical and rotational movements, butacting independently when extending or retracting to pick or placeworkpieces. Additionally, two or possibly more workpieces may be locatedside by side on paddles or other devices fixed to each robot arm.Furthermore, the robots may operate in an over/under fashion to reducetheir geometrical profile and minimize the transfer time of post- andpre-processed workpieces. The robot arm structure can be made to avoidany bearing surfaces passing directly over a workpiece and thus helpingensure cleaner, lowerparticle-on workpiece contamination duringoperation.

In another embodiment, a slit door could be used to isolate the processchamber environment from that of the transfer chamber. Such a door couldwork utilizing vertical motions to allow passage of workpieces throughthe process chamber doorway. Small horizontal motion could be used toseal or unseal the door from the doorway. Both motions allow for a verycompact door and contribute to minimizing the footprint of the system.Such a door could be made to seal off positive pressure in the processchamber while the transfer chamber operated at negative pressure. Inanother embodiment, a process chamber could be serviced at atmosphericpressure while the transfer chamber remained at partial or near-vacuum.

In another embodiment, the transfer chamber could be designed to dockthree or more process chambers, each capable of processing two or moreworkpieces side by side. Each process chamber could be designed as amodular entity, requiring a minimum amount of effort to mount to andcommunicate with the main transfer chamber and its elements.Additionally, multiple process chambers mounted to the transfer chambermight each provide the same or different process capability.

In another embodiment, pre- or post-process stations could be located inthe transfer chamber and made accessible to the vacuum robot handler.Examples of such processes include, but are not limited to, preheatingor cooling of workpieces and workpiece orientation and alignment.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention willbecome more apparent to those skilled in the art from the followingdetailed description in conjunction with the appended drawings in which:

FIGS. 1-(1) through 1-(8) illustrates the workpiece transport path of aprior art workpiece handling system.

FIGS. 2-(1) through 2-(6) illustrates a load lock transfer system of aprior art workpiece handling system.

FIG. 3A illustrates a prior art workpiece handling system with tworobots.

FIG. 3B illustrates the workpiece transport path in the prior art systemof FIG. 3A.

FIG. 4 is a simplified side cross-sectional view of a workpiece handlingsystem according to an exemplary embodiment of the present invention.

FIG. 5 is a simplified top cross-sectional view of a workpiece handlingsystem according to an exemplary embodiment of the present invention.

FIG. 6A is a top, front perspective view of a workpiece handling systemaccording to an exemplary embodiment of the present invention.

FIG. 6B is a top, rear perspective view of a workpiece handling systemaccording to an exemplary embodiment of the present invention.

FIG. 7A is a top plan view of a vacuum transfer robot according to anexemplary embodiment of the present invention.

FIG. 7B is a top, rear perspective view of a vacuum transfer robotaccording to an exemplary embodiment of the present invention.

FIG. 8A is a top plan view of a rotational door according to anexemplary embodiment of the present invention.

FIG. 8B is a simplified side view of load locks having rotational doorsin a closed position according to an exemplary embodiment of the presentinvention.

FIG. 8C is a simplified side view of load locks having rotational doorsin an open position according to an exemplary embodiment of the presentinvention.

FIG. 8D is a simplified side view illustrating the rotational and linearmotions used to open and close rotational doors according to anexemplary embodiment of the present invention.

FIG. 9A is a top plan view of a linear door assembly according to anexemplary embodiment of the present invention.

FIG. 9B is a simplified side view of a linear door assembly according toan exemplary embodiment of the present invention.

FIG. 9C is a top cross-sectional view of a linear door assemblyaccording to an exemplary embodiment of the present invention.

FIG. 9D is a side view of a linear door assembly according to anexemplary embodiment of the present invention.

FIG. 10A is a side cross-sectional view of a linear door assemblyaccording to an alternate embodiment of the present invention.

FIG. 10B is a side cross-sectional view of a linear door assemblyaccording to an alternate embodiment of the present invention.

FIG. 11 illustrates a side view of a rotary mechanism.

FIG. 12 illustrates an alternative embodiment of a rotary mechanism.

DESCRIPTION

The following description is presented to enable any person skilled inthe art to make and use the invention. Descriptions of specific designsare provided as examples. Various modifications to the embodiment willbe readily apparent to those skilled in the art, and the genericprinciples defined herein may be applied to other embodiments andapplications without departing from the spirit and scope of theinvention. Thus, the present invention is not intended to be limited tothe embodiment shown, but is to be accorded the widest scope consistentwith the principles and features disclosed herein.

FIG. 4 is a simplified side cross-sectional view of a semiconductorworkpiece handling system, generally indicated at 400, according to anembodiment of the present invention. As shown in FIG. 4, system 400includes a workpiece cassette holder 402 which may be in a clean roomenvironment, an atmospheric robot 404, an upper load lock 406 a, a lowerload lock 406 b, a vacuum transport chamber 408 and a process chamber410. System 400 allows workpieces to be transported from cassette holder402 to process chamber 410 for processing using a compact and simplifiedload lock and robotics design with high throughput and a low potentialfor contamination. Cassettes of workpieces to be processed are initiallyprovided at cassette holder 402. Atmospheric robot 404 includes one ormore paddle(s) 412 for supporting and transporting workpieces and ashaft 414 for rotating and/or raising or lowering paddle(s) 412. Whenthe robot retrieves workpieces from a cassette, the shaft is rotated andpositioned so paddle(s) 412 faces the cassette. Paddle(s) 412 extendshorizontally to retrieve one or more workpieces and then retracts withthe workpieces on paddle(s) 412. Shaft 414 then rotates and moves sopaddle(s) 412 face load locks 406 a and 406 b. The shaft is raised orlowered to align the paddle with shelves in either load lock 406 a or406 b in the course of which all motions due to independent control mayoccur simultaneously or in sequence. Generally, at any given time one ofthe load locks will be open to atmospheric robot 404, while workpiecesin the other load lock are being processed at vacuum pressures.Paddle(s) 412 then may extend horizontally to deposit the workpiece(s)in the appropriate load lock. Atmospheric robot 404 also removesworkpiece(s) from the load locks and deposits the processed workpiece(s)in a cassette in a similar manner.

The load locks contain one or more shelves 416 a and 416 b to holdworkpieces. The shelves may be cooled to provide a cooling station forworkpieces after processing. In alternate embodiments, a cassette-likeholder may be loaded into the load lock rather than providing a shelf orshelves in the load lock. The load locks are sealed on the outside bylinear doors 418 a and 418 b. The top linear door 418 a may be raised toexpose an opening through which workpieces may be loaded into, orunloaded from, upper load lock 406 a. The bottom linear door 418 b maybe lowered to expose a similar opening through which workpieces may beloaded into, or unloaded from, lower load lock 406 b.

After atmospheric robot 404 removes processed workpieces from a loadlock and reloads it with new workpieces, the linear door is closed andthe load lock is evacuated to vacuum pressure to match the pressure ofthe vacuum transport chamber 408. A rotational door 420 a or 420 b isthen opened to allow a vacuum transport robot 422 to access theworkpieces. An upper rotational drive (not shown) moves upper rotationaldoor 420 a linearly a slight distance away from the inner wall 424 a ofthe upper load lock and rotates it. The rotational drive raises orlowers the door to expose an opening through which workpieces may beretrieved from shelves 416 a before processing and returned afterprocessing. A lower rotational drive (not shown) moves lower rotationaldoor 420 b in a similar manner back and upward or downward from wall 424b to allow access to workpieces in lower load lock 406 b.

The dual load lock system shown in FIG. 4 allows almost continuousprocessing without significant down time for providing new workpiecesfrom the atmospheric clean room to the vacuum processing environment.When workpieces are being loaded into one of the load locks (for exampleupper load lock 406 a), the other load lock 406 b is at vacuum pressure.For the upper load lock 406 a, linear door 418 a would be open andatmospheric robot 404 would remove processed workpieces and reload theload lock with new workpieces. Rotational door 420 a would be closed toprovide a seal against the vacuum pressure of vacuum transport chamber408. At the same time, rotational door 420 b would be open and lineardoor 418 b would be closed to allow workpieces in lower load lock 406 bto be accessed for processing.

After loading, linear door 418 a is closed and upper load lock 406 a isevacuated by a vacuum pump (not shown). When the appropriate pressure isobtained, rotational door 420 a may be opened. In order to allow nearcontinuous processing, upper load lock 406 a may be evacuated androtational door 420 a may be opened before or just as the penultimateprocessed workpiece is returned to lower load lock 406 b. A newworkpiece from upper load lock 406 a is then exchanged with the lastprocessed workpiece in process chamber 410 which is returned to lowerload lock 406 b. The rotational door 420 b is then closed and thepressure in lower load lock 406 b is raised to equilibrium with thesurrounding environment (which may be a clean room at atmosphericpressure). Linear door 418 b is then opened and atmospheric robot 404removes processed workpieces and reloads new workpieces in lower loadlock 406 b. The process then continues such that new workpieces arealways or nearly always available from one of the load locks forprocessing in the vacuum environment.

The vacuum transport robot 422 retrieves new workpieces from whicheverload lock is open and places the workpieces in process chamber 410 forprocessing. The vacuum transport robot 422 also removes processedworkpieces from process chamber 410 and returns them to the respectiveload lock. Vacuum transport robot 422 is designed to minimize thetransport time required to remove a processed workpiece from, and reloada new workpiece into, the process chamber 410. The transport time isdown time for process chamber 410 which reduces throughput, so it isimportant to keep the transport time short.

The transport robot has one or more upper paddle(s) 426 a and lowerpaddle(s) 426 b for supporting and transporting workpieces and a shaft428 for rotating and/or raising or lowering the paddles. The robot hasupper arms 430 a and lower arms 430 b affixed to a four-bar linkage forextending and retracting paddles 426 a and 426 b, respectively. Forpurposes of the following discussion, it will be assumed that rotationaldoor 420 a is open and that new workpieces are available in upper loadlock 406 a, although it is understood that a similar process is usedwhen workpieces are available in lower load lock 406 b. Initially, it isassumed that the last workpiece from lower load lock 406 b is beingprocessed in process chamber 410 and that the second to last processedworkpiece was just returned to lower load lock 406 b. At this time, bothupper and lower rotational doors 420 a and 420 b are open and upper loadlock 406 a contains new workpieces to be processed. Shaft 428 is thenraised to align one of the paddles (for example upper paddle 426 a) witha new workpiece on a shelf in upper load lock 406 a. Arm 430 a thenextends and paddle 426 a retrieves a new workpiece from the upper loadlock. The arm 430 a then retracts and shaft 428 rotates 180 degrees sothe arms and paddles face the process chamber. Both arms are fullyretracted when the shaft rotates. This minimizes the rotation diameterand allows a relatively compact transport chamber to be used. This isparticularly desirable when 300 millimeter or larger workpieces arebeing handled. After rotation, the shaft is raised or lowered asnecessary to align paddle 426 b with the processed workpiece in processchamber 410. Of course, in some embodiments, this alignment may occurprior to or during rotation. The processed workpiece may remain at ornear a process station 432 for removal or, in some process chambers, theworkpiece may be raised on pins or other mechanisms for removal. A door434 may be opened to allow the processed workpiece to be removed and anew workpiece to be placed in the process chamber. The door may be alinear or rotational door as described above or may be a conventionaldoor system. The door 434 may be opened as the transport robot 422rotates and aligns, so there is no extra delay (or the robot may befully rotated and aligned prior to completion of processing, in whichcase the door is opened at the completion of processing).

Arm 430 b then extends and paddle 426 b retrieves the processedworkpiece.

Arm 430 b then retracts and shaft 428 is lowered to align paddle 426 awith the desired position for depositing a new workpiece in the processchamber. Arm 430 a extends and a new workpiece is deposited in processchamber 410 from paddle 426 a. Arm 430 a then retracts. The shaft thenrotates 180 degrees with both arms in the retracted position.

Shaft 428 is then lowered or raised to align with the respective shelfin lower load lock 406 b. Arm 430 b extends and returns the lastprocessed workpiece to lower load lock 406 b. Arm 430 b retracts androtational door 420 b is closed. The pressure in lower load lock 406 bis then raised so the processed workpieces can be removed as describedabove. Shaft 428 then raises paddle 426 a to align with a new workpiecein upper load lock 406 a. Arm 430 a extends, picks up and retracts witha new workpiece. Transport robot 422 rotates and the empty lower paddle426 b is aligned to retrieve the processed workpiece from processchamber 410. When processing is complete, door 434 opens and arm 430 bextends and retracts with the processed workpiece. The new workpiece isthen deposited in the process chamber as described above. The robotrotates again and arm 430 b extends and retracts to deposit theprocessed workpiece on the applicable shelf of upper load lock 406 a.Arm 430 a extends and retracts to obtain a new workpiece and the processcontinues until the last workpiece from upper load lock 406 a is inprocess chamber 410. By that time, lower load lock 406 b has beenunloaded and reloaded with new unprocessed workpieces and then pumpeddown, after which lower rotational door 420 b is opened.

FIG. 5 is a top cross-sectional view of a workpiece handling systemaccording to an embodiment of the present invention which allows fordual side-by-side workpiece processing. The robots, load locks andprocess chamber are all designed to handle two (or possibly more)workpieces at a time. As a result, a significant amount of the machineryand control mechanisms are shared while throughput is doubled (or more).As shown in FIG. 5, two or more workpiece cassette holders 402 and 502may be provided side-by-side. Atmospheric robot 404 may be positioned ona track 505 which allows the robot to move horizontally to align witheither cassette holder 402 or 502. Upper load lock 406 a and lower loadlock 406 b (not shown in FIG. 5) each have side by side positions forworkpieces on each of the shelves 416 a or 416 b (not shown in FIG. 5).Transport robot 422 has dual paddles on each arm 430 a and 430 b. Upperarm 430 a supports paddles 426 a and 526 a. Lower arm 430 b supportspaddles 426 b and 526 b. The robot is thereby capable of depositing orretrieving two workpieces at a time from shelves 416 a or 416 b. Forinstance, arm 430 b may extend to deposit two processed workpieces in arespective load lock. Shaft 428 may then be raised or lowered to alignpaddles 426 a and 526 a with new workpieces on a different shelf. Arm430 a may then extend to retrieve the two new workpieces for processing.Once both of the arms are retracted, shaft 428 may rotate, so thepaddles face the process chamber 410. The process chamber is designed tocontain at least two process stations 432 and 532. Door 434 is raisedand arm 430 b extends to retrieve the two processed workpieces from theprocess chamber 410. After arm 430 b retracts with the processedworkpieces, the shaft is raised or lowered to align the new workpieceswith the desired position in the process chamber. Arm 430 a then extendsto deposit the new workpieces for processing. The process continues asdescribed above with two workpieces processed at a time.

FIG. 6A is a top front perspective view and FIG. 6B is a top backperspective view of a workpiece handling system according to anembodiment of the present invention which illustrate portions of a framestructure which may be used to support and expand the workpiece handlingsystem. As shown in FIGS. 6A and 6B cassette holders 402 and 502 arepart of a cassette auto loader system 602. An operator interface panel601 is provided adjacent to the auto loader system 602 and another maybe positioned on the main frame assembly 608. The operator interfacepanel 601 allows an operator to program the system and adjustoperational parameters. It will be understood that the various robots,doors and other mechanisms may be controlled by programmable softwareexecuted by a processing unit. Accordingly, the particular order andprocess steps used to manipulate workpieces may be modified for aparticular application using software controls. For instance, it may bedesirable in some embodiments to have the upper paddles 426 a and 526 ahandle processed workpieces, so a robot arm does not pass over theworkpieces after processing which could expose the underlying workpiecesto shed particles. In such an embodiment, the software would cause thelower arm 430 b to be used for new workpieces prior to processing. Itwill be readily apparent that any variety of process steps and sequencesmay be implemented by modifying the software controlling the robots,doors and other mechanisms.

In the embodiment shown in FIGS. 6A and 6B a mini-environment 604 with aHepa or Ulpa filter may positioned between the auto loader system 602and the load locks 406 a and 406 b for atmospheric robot 404. The track505 for the atmospheric robot is also thereby contained in themini-environment.

As shown in FIG. 6A, linear door 418 a is raised to expose slit 618 a toaccess upper load lock 406 a and linear door 418 b is lowered to exposeslit 618 b to access lower load lock 406 b. Although both doors are openin FIG. 6A for purposes of illustration, normally only one door would beopen at a time as described above. The linear doors are aligned on rail619 as shown in FIG. 6B which allows the doors to be raised and lowered.The linear doors are attached to load lock frame 606.

Upper rotational door 420 a is also shown in the open position in FIG.6A for illustrative purposes, although as described above normally doors420 a and 418 a would not be open at the same time. The rotational drivemechanism for opening the rotational doors is positioned adjacent toload lock frame 606 as shown at position 620 in FIGS. 6A and 6B. As willbe described further below, the rotational drive mechanism moves therotational door 420 a linearly slightly back from the doorway prior torotation. Rotational door 420 a is then rotated up (or down) to open it.When it is closed, it is rotated down (or up) and then moved linearlyslightly forward to seal the opening. Lower rotational door 420 b uses asimilar motion, although it is rotated down (or up) when it is open.While the drive mechanisms and motions for these doors is more complexthan for the linear doors, they allow for two very compact doors to beused one above the other for the two load locks.

Main frame assembly 608 provides a support for transport chamber 408.Transport robot 422 is shown in FIGS. 6A and 6B with upper arm 430 aextended into upper load lock 406 a. Lower arm 430 b is retracted.

The transport chamber shown in FIGS. 6A and 6B supports multiple processchambers through multiple docks. Process chamber 410 is connected to oneof the docks and is supported by process module frame 610. Additionaldocks are shown at 635 (in FIG. 6A) and 636 (in FIG. 6B). An additionalprocess chamber may be connected to each dock 635 and 636. As shown inFIG. 6A, each dock may be provided with slit door 634. With additionalprocess chambers attached to docks 635 and 636, as many as sixworkpieces may be processed at a time. When process chambers areconnected to docks 635 and 636, a similar process to that describedabove is used to load and unload workpieces, but the robot is programmedto rotate only 90 degrees when aligning with the additional processchambers. The processing may be staggered, so vacuum transport robot 422can remove and load workpieces in each process chamber without delayingprocessing in the other chambers.

For instance, the robot may first rotate to align with a process chamberat dock 635 and then remove two processed workpieces and load two newworkpieces. The robot then rotates 90 degrees back to the load locks todeposit the processed workpieces and retrieve two new workpieces. Therobot may then rotate 180 degrees to process chamber 410, remove twoprocessed workpieces and load the new workpieces. The robot then rotates180 degrees back to the load locks to deposit the processed workpiecesand retrieve two new workpieces. The robot then rotates 90 degrees toalign with a process chamber at dock 636, remove two processedworkpieces and load the new workpieces. The robot then rotates 90degrees back to the load locks to deposit the processed workpieces andretrieve two new workpieces. The process then continues back to theprocess chamber at dock 635. With such a configuration, a very highthroughput may be achieved.

In addition, if the process chambers at each dock were different, therobot might be programmed to move workpieces from one process chamber toanother process chamber. For instance, it may be desired to process newworkpieces in a process chamber at dock 635 and then move the processedworkpieces from dock 635 to a second process in process chamber 410. Insuch an embodiment, the robot would retrieve workpieces from dock 635and rotate 90 degrees to process chamber 410 rather than returning tothe load locks. Workpieces from process chamber 410 may be removed andthe workpieces from dock 635 may be deposited using the under/overtransport robot arms 430 a and 430 b as described above. The robot couldthen move the workpieces from process chamber 410 back to the load lock,or in some embodiments, the workpieces may be moved to dock 636 forfurther processing. Through programmable software control any variety ofprocesses may be supported with high throughput.

FIG. 7A is a top plan view, and FIG. 7B is a top, rear perspective view,of a vacuum transfer robot according to an exemplary embodiment of thepresent invention. The robot is shown with upper arm 430 a extended andlower arm 430 b retracted. As shown in FIGS. 7A and 7B, upper arm 430 ahas four bars connected by rotational joints. Thin base bar 702 a isconnected to shaft 428 by rotational joint 712 a. The other end of thinbase bar 702 a is connected to rotational joint 716 a. A wide base bar704 a is adjacent on the inside of thin base bar 702 a and is connectedto shaft 428 by rotational joint 714 a. The other end of the wide basebar 704 a is connected to rotational joint 718 a. Thin fore bar 706 a isconnected to rotational joint 716 a and extends to a split support 725 awhich supports paddles 426 a and 526 a. Thin fore bar 706 a is connectedto split support 725 a at rotational joint 720 a. A wide fore bar 708 ais adjacent on the outside of thin fore bar 706 a and is connected torotational joint 718 a. The wide fore bar 708 a connects to the splitsupport at rotational joint 722 a.

A driving shaft may be directly coupled to wide base bar 704 a throughrotational joint 714 a. Rotation of the shaft results in an equalrotation of wide base bar 704 a. An opposite rotational movement istransmitted through wide base bar 704 a into thin fore bar 706 a bycounter rotating elements hard-coupled to each through rotational joints718 a and 716 a respectively. Both thin base bar 702 a and wide fore bar708 a follow the rotation of wide base bar 704 a and thin fore bar 706a, respectively. Hence, a purely linear motion is provided to the splitsupport 725 a. The arrangement of the bars ensures that the center ofthe split support stays aligned so the paddles move linearly when theyextend or retract.

Arm 430 b has a similar structure. The corresponding parts are labeledwith the same number as used to describe arm 430 a except that a suffixof “b” has been used instead of “a”. It will be noted, however, thatsplit support 725 a is mounted above bars 706 a and 708 a while splitsupport 725 b is mounted below bars 706 b and 708 b. It will also benoted that bars 706 a and 708 a are mounted above rotational joints 718a and 716 a which provides a clearance for the lower split support 725 bto pass under upper arm 430 a. This structure allows the arm to use anover/under motion to deposit and retrieve workpieces. This structurealso allows arm 430 b to be extended and retracted without passingpaddles 426 b and 526 b directly under any of the rotational joints ofupper arm 430 a. This helps minimize the potential of shed particlesfrom the rotational joints from dropping onto workpieces supported bypaddles 426 b and 526 b.

The operation of rotational doors 420 a and 420 b will now be describedwith reference to FIGS. 8A-8D. FIG. 8A is a top view of rotational door420 a in the closed position and portions of rotational drive mechanism620. The arrows indicate that a linear motion and a rotational motionmay be imparted on rotational door 420 a by rotational drive mechanism620. FIG. 8B is a side cross-section of load locks 406 a and 406 bshowing rotational doors 420 a and 420 b in the closed position. Therotational drive mechanism has pushed the doors against inner walls 424a and 424 b to seal the doors closed. An o-ring or other mechanism maybe provided at the interface of the doors and inner walls to provide aseal. FIG. 8C illustrates rotational doors 420 a and 420 b in the openposition. As indicated by the arrows, rotational drive mechanism 620moves the doors linearly slightly away from inner walls 424 a and 424 band then rotates rotational door 420 a up and rotational door 420 b downto open the doors. FIG. 8D is a side cross-sectional view furtherillustrating the motions which may be imparted on rotational door 420 a.As shown in FIG. 8D, when the rotational door 420 a is rotated to theclosed position it may still be a short distance from wall 424 a.Rotational drive mechanism 620 can then move the door linearly towardwall 424 a to seal the door.

The advantage of having such rotational doors 420 a and 420 b within theload locks comes from the fact that the load lock pressure is oftengreater than that in the transfer chamber (during workpieceloading/unloading to atmosphere) but never significantly less than it.Therefore, this rotational door is held shut by the pressuredifferential when the workpieces are being loaded or unloaded from thatload lock. This insures that the pressure seal is well made and that themechanism which translates the rotating door does not bear a heavy load.Further, the door mechanism is housed within the load lock and does notallow particles to fall directly into the workpiece transfer chamber oronto the load lock chamber below.

The motion of linear doors 418 a and 418 b are also shown in FIGS. 8Band 8C. The linear doors will now be further described in conjunctionwith FIGS. 9A-9D. FIG. 9A is a top cross-sectional view of upper loadlock 406 a and a top view of linear door 418 a. Linear door 418 a ismounted on a linear motion track or rail 619 along which the door isguided when it is moved into open or closed position. FIG. 9D is a sideview of upper load lock 406 a and linear door 418 a which shows rail619. Linear door 418 a further may include sensor 901 to sense thepresence or absence of workpieces. When a workpiece is sensed, a signalis provided by the sensor 901 to a mechanism for sliding linear door 418a upward along rail 619 to a position that allows workpieces to passthrough the doorway of upper load lock 406 a. The motion of the door inthe embodiment shown in FIG. 9D is accomplished by a pneumatic cylinderbut it will be appreciated that many alternatives, such as linearbearings, lead screws, and motors also may be employed to move lineardoor 418 a.

FIG. 9B is a side cross-section of upper load lock 406 a and linear door418 a with arrows indicating the directions in which linear door 418 amay be moved. FIG. 9C is a top cross-section of upper load lock 406 aand linear door 418 a which shows the mechanism used to seal the doorwhen it is closed. As shown in FIG. 9C, linear door 418 a includes doorframe 902 which forms a recess. A door plate 904 is positioned in therecess and is connected to the door frame 902 by an extendableconnector, such as spring 906. When door frame 902 is lowered over thedoorway, door plate 904 may be extended to seal the door. When vacuumprocessing pressures are used, the pressure differential may then causedoor plate 904 to seal the doorway. O-rings 908 or other mechanisms maybe used to provide a good seal. Electromagnets 910 may also be used toattract door plate 904 and seal the doorway. In such embodiments, doorplate 904 could comprise a magnetic material capable of being attractedto electromagnets 910 or such material could be mounted to door plate904, if it is non-magnetic, for the same result. Such magnets could bemounted outside the o-ring seal such that they are not in vacuum whenthe load lock is evacuated.

When workpieces have been loaded into the load lock and it is desired toseal upper load lock 406 a, the linear door 428 a, which is positionedabove the doorway, is lowered to cover the doorway. Electromagnets 910are activated and door plate 904 extends toward the electromagnets toform a seal against o-rings 908. When it is desired to transferworkpieces out of upper load lock 406 a, upper load lock 406 a isre-pressurized to equalize with the pressure of the surroundingenvironment. If electromagnets 910 are being used, they are deactivatedor made to provide a repelling force. Spring 906 or other extensiondevice in conjunction with the repulsive electromagnetic force thenretracts door plate 904 to unseal the doorway. Linear door 418 a is thenraised along rail 619 to open the doorway and allow workpieces to beremoved from upper load lock 406 a. It will be understood that a similarmechanism is used for lower linear door 418 b except that the door islowered when it is opened.

Many alternatives to the embodiment shown in FIGS. 9A-9D are possible.For example, instead of an electromagnet, other devices may be employedto extend door plate 904 to seal the doorway. As shown in FIG. 10A,inflatable tube 1006 may be inflated to push door plate 904 against thedoorway. The inflatable tube 1006 is deflated to unseal and open thedoor. As shown in FIG. 10B, a pneumatic cylinder 1008 may also be usedto push door plate 904 against, and retract door plate 904 from, thedoorway. The ease with which door plate 904 may be extended andretracted allows the door to function as an over-pressure valve and a“back to atmosphere” switch.

FIG. 11 illustrates a side view of rotary mechanism 620. Rotarymechanism 620 is used to rotate and translate rotational doors 420 a and420 b for opening and sealing the system. The mechanism operates on theoutside of load locks 406 a and 406 b. The following discussiondescribes mechanism 620 of the lower load lock 406 b. A similardiscussion applies to the mechanism of upper load lock 406 a. Rotationaldoor 420 b and shaft 421 b are secured to slide block 1101 and allowedto rotate therein. Outside slide block 1101, rotary stop 1102 and gear1103 are rigidly fixed to and rotate with the shaft. The slide block1101 is allowed to translate on linear slide 1104 and is acted on byspring 1105 so that it rests against hard stop 1106. Interacting withand engaging gear 1103 is a linear rack 1107 which can translate onslide 1108 and is motivated by piston 1109. As shown, linear rack 1107is being pulled into piston 1109 such that rotary stop 1102 is pushedagainst block 1110. This position of the mechanism places rotationaldoor 420 b in the orientation shown in FIG. 8C. When piston 1109 pusheson linear rack 1107, gear 1103 is rotated clockwise as are rotary top1102 and rotational door 420 b. Spring 1105 reacts against any impendingtranslation of slide block 1101 and keeps it pushed against hard stop1106. Once rotary top 1102 comes into contact with stop 1111, rotarymotion stops. Piston 1109, However, continues to push linear rack 1107into gear 1103. By virtue of rotational impedance, slide block 1101 istranslated on linear slide 1104 into spring 1105. This motion is coupledto rotational door 420 b which pushes against a sealing mechanism thedoorway and isolates lower load lock 406 b from vacuum transport chamber408. In this mode, the door is considered closed. Both slide block 1101and the shaft of rotational door 420 b are sealed by means of 0-rings orother devices such as bellows to isolate lower load lock 406 b from thesurrounding environment.

When rotational door 420 b is opened, piston 1109 retracts. In doing so,spring 1105 pushes slide block 1101 into hard stop 1106. Since there isno relative motion between linear rack 1107 and gear 1103 during thismovement, pure translation is realized and rotational door 420 b movesaway from the doorway and its seal. Once slide block 1101 hard stops,linear rack 1107 continues to be pulled by piston 1109 and rotationalmotion is imparted to rotational door 420 b through gear 1103. Finally,rotary stop 1102 makes contact with bock 1110 and rotation stops. Again,rotational door 420 b is now in the open position.

In alternative embodiments, piston 1109 could be replaced by a motordriven lead screw or any other translational driving mechanism. Linearrack 1107 and gear 1103 could interface through friction and eliminatetooth contacts. Spring 1105 could be replaced by a piston or inflatablebladder.

In another embodiment shown in FIG. 12, rotation and translation couldbe controlled separately by linkage 1201 and wedge 1202. Sensors oncontrol pistons 1203 and 1204 could indicate the position of the rotarydoor and coordinate the motions. To close, piston 1203 would extend androtate linkage 1201 counter clockwise which is attached to rotationaldoor 420 a or 420 b and is contained in slide block 1101. Once properposition was achieved, which could be through the use of a hard stop,control piston 1204 would extend pushing wedge 1202 into roller 1205.

Since roller 1205 is fixed to slide block 1101, translation and sealingof rotational door 420 a or 420 b to their respective doorways isachieved. To open, control piston 1204 is retracted and spring 1105pushes back on slide block 1101. Once in proper horizontal position,piston 1203 retracts and rotates rotational door 420 a or 420 b to anopen position.

The foregoing description is presented to enable any person skilled inthe art to make and use the invention. Descriptions of specific designsare provided only as examples. Various modifications to the exemplaryembodiments will be readily apparent to those skilled in the art, andthe generic principles defined herein may be applied to otherembodiments and applications without departing from the spirit and scopeof the invention. Thus, the present invention is not intended to belimited to the embodiments shown, but is to be accorded the widest scopeconsistent with the principles and features disclosed herein.

We claim:
 1. A door system for sealing a doorway between two chambers ina workpiece processing system, the door system comprising: a door sizedto seal the doorway; means for moving the door against the doorway toseal the doorway; means for retracting the door from the doorway tounseal the doorway; and means for rotating the door in a verticaldirection around an axis substantially parallel to the orientation ofthe doorway such that workpieces may pass through the doorway, whereinthe means for rotating the door comprises: a shaft coupled to the door;a rotation gear coupled to the shaft; and a linear gear operativelyengaged with the rotation gear such that linear motion of the lineargear relative to the rotation gear causes rotation of the rotationalgear.
 2. The door system of claim 1, wherein the means for movingcomprises: a housing configured to support the shaft via an apertureformed through the housing and to slidedly move in a linear directiontoward the doorway and away from the doorway; a rotary stop blockcoupled to the housing; and a rotary stop coupled to the shaft, therotary stop configured to stop rotation of the shaft in response to therotary stop impinging the rotary stop block, whereby further linearmotion of the linear gear relative to the rotation gear causes thehousing to move in a linear direction toward the doorway.
 3. The doorsystem of claim 1, wherein the means for retracting comprises: a housingconfigured to support the shaft via an aperture formed through thehousing and to slidedly move in a linear direction toward the doorwayand away from the doorway; and a spring configured to apply a force tothe housing to slidedly move the housing in a linear direction away fromthe doorway.
 4. A door system for sealing a doorway between two chambersin a workpiece processing system, the door system comprising: a doorsized to seal the doorway; means for moving the door against the doorwayto seal the doorway; means for retracting the door from the doorway tounseal the doorway; and means for rotating the door in a verticaldirection around an axis substantially parallel to the orientation ofthe doorway such that workpieces may pass through the doorway, whereinthe means for rotating comprises: a shaft coupled to the door; a linkagemember coupled to the shaft; and a piston coupled to the linkage suchthat actuation of the piston causes rotation of the shaft.
 5. The doorsystem of claim 4, wherein the means for moving comprises a wedge memberconfigured to move the shaft in a linear direction toward the doorway inresponse to actuation of the wedge member.
 6. A door system for sealinga doorway between two chambers in a workpiece processing system, thedoor system comprising: a door sized to seal the doorway, the doorhaving an open position that allows workpieces to pass through thedoorway and a sealing position that orients the door to seal thedoorway; a housing having an open position rotation stop and a sealingposition rotation stop; a shaft coupled to the door and rotationallycoupled to the housing; a rotation gear coupled to the shaft wherein therotation gear includes a rotary stop which contacts the open positionrotation stop when the door is in the open position and which contactsthe sealing position rotation stop when the door is in the sealingposition; a linear gear operatively engaged with the rotation gear suchthat linear motion of the linear gear relative to the rotation gearcauses rotation of the door in a vertical direction between the openposition and the sealed position.
 7. The door system of claim 6, furthercomprising a spring coupled to the housing wherein the spring pushes thehousing in a direction substantially parallel to the direction of linearmotion of the linear gear.
 8. The door system of claim 6, wherein thehousing is configured to slidedly move between a first position and asecond position in response to movement of the linear gear, the firstposition compressing the door against the doorway when the door is inthe sealing position and the second position providing a space betweenthe door and the doorway when the door is not in the sealing position.9. The door system of claim 6, wherein the linear gear is coupled to apiston to provide the linear motion.
 10. The door system of claim 6,wherein the linear gear is coupled to a lead screw to provide the linearmotion.
 11. The door system of claim 6, further comprising a sealingmember coupled to a peripheral portion of the doorway to seal thedoorway when the door is in the sealing position.
 12. A door system forsealing a doorway between a first chamber and a second chamber, the doorsystem comprising: a door having an area larger than the doorway; ashaft coupled to the door, the shaft configured to rotate the door in avertical direction between an open position that allows workpieces topass through the doorway and a closed position that orients the door toseal the doorway; and a rotable drive, coupled to the shaft, configuredto rotatably actuate the shaft to rotate the door between the openposition and the closed position and to linearly translate the doorbetween a sealed position and an unsealed position, the sealed positioncompressing the door against the doorway when the door is in a closedposition and the unsealed position allowing the door to move between theclosed position and the open position.
 13. The door system of claim 12,wherein the rotable drive comprises: a rotation gear coupled to theshaft; and a linear gear operatively engaged with the rotation gear suchthat linear motion of the linear gear relative to the rotation gearcauses rotation of the rotation gear and the door between the openposition and the sealed position.
 14. The door system of claim 13,wherein the rotable drive further comprises a housing for supporting theshaft, the housing configured to slidedly move the shaft between thesealed position and the unsealed position in response to actuation ofthe linear gear.
 15. The door system of claim 13, wherein the rotationgear includes a rotary stop which contacts an open position rotationstop when the door is in the open position and which contacts a sealingposition rotation stop when the door is in the sealing position.
 16. Thedoor system of claim 12, wherein the rotable drive comprises: a linkagecoupled to the shaft; a piston coupled to the linkage such thatactuation of the piston causes rotation of the door between the openposition and the closed position; and a wedge member configured tolinearly translate the rotable drive to move door between the sealedposition and the unsealed position in response to actuation of the wedgemember.
 17. The door system of claim 16, further comprising sensors forsensing a position of the door and coordinating actuation of the pistonand the wedge member such that the door is moved to the unsealedposition before the door is moved between the open position and theclosed position.
 18. The door system of claim 16, wherein the rotabledrive further comprises a housing for supporting the shaft, the housingconfigured to slidedly move the shaft between the sealed position andthe unsealed position in response to actuation of the wedge member.